Herniaria glabra

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Herniaria glabra is a relatively unknown perennial that deserves to be used more often in our gardens. In Plant nurseries is is known as ‘Green Carpet’.. This lovely bright green creeper spreads effortlessly in all directions filling up to two feet per plant. The tiny tight green leaves form an extremely dense evergreen ground-cover.

Known to be nearly indestructible, Herniaria glabra is an excellent choice for growing between flagstones or as a lawn substitute. It is soft to walk on and can take quite a bit of foot traffic, as long as it is not continual. Never growing taller than 4cm (1½in), this fairly flat plant spreads 30 to 60cm (12 to 24in). The deep green foliage creates a dense evergreen carpet, becoming bronze in winter and bears minuscule, insignificant white flowers in early summer. The growth rate is fairly slow and easy to control and plants can be easily divided in spring.

Herniaria glabra prefers well drained soil in full sun or light shade. This easy-care perennial is well-rooted with one long tap root (as opposed to many surface roots like Creeping Thyme), making it drought tolerant and helping with water conservation.
It is not fussy about soil and will happily grow in poor soil and gravel. It is also extremely hardy to around minus 30°C (-20°F). The plants is gently coumarin-scented, the sweet odour readily recognised as the scent of newly-mown hay

The trailing habit of Herniaria glabra is also useful for rock gardens walls and bedding schemes. They are useful for tumbling over the edges of container plantings, the vibrant green perks up silver-grey leaved plants and offsets bright blooms and darker green foliage.

Sowing: Sow in spring or in autumn.
Prepare pots or trays with good free draining seed compost (John Innes or similar), moisten by standing in water, then drain. Surface sow two seeds per pot or cell and press them gently down to firm them in. Cover the seed with a fine layer of vermiculite if you have it. Seal pots in a polythene bag or cover trays with clear plastic lids until after germination. It is important to keep soil slightly moist but not wet. Remove the polythene bag once the first seedlings appear. Germination usually takes 14 days at temperatures around 20 to 22°C (68 to 71°F).
When they are large enough to handle transplant the seedlings to 7 to 10cm (3 to 4in) pots to grow on. Place the pots in a coldframe or unheated greenhouse to grow on.
Before transplanting the plants outdoors, hardened the plants off gradually by placing them outside in a sheltered position during the day; bring them in at night to avoid frosts. Space plants 20cm (8in) apart.

Cultivation:
Cover substrate with vermiculite or mulch to retain water and keep your eye on small plants until they establish themselves. A relatively low maintenance perennial, simply remove damaged foliage in spring and fertilise with a complete balanced fertiliser, don't fertilise after mid September.

Origin:
Native to temperate areas of Europe and Russian Asia, extending into Scandinavia, but not to high latitudes. A native of Britain, especially southern and central England.
The genus Herniaria was formerly included in the family Illecebraceae, but is now segregated with the Caryophyllaceae, related to Carnations and Dianthus.
There are very few species of the genus. They are small annuals or undershrubs, with small green flowers crowding along the stems intermixed with leaves.

Nomenclature:
Pronounced her-nee-ah-ree-a gla-bra, it is named for its historical use as a medicinal plant, It was formerly used to treat cuts - herniated skin. In this capacity, it also received its common name of Rupturewort.
It is also referred to as Smooth Rupturewort, the species name glabra means 'smooth' or 'hairless'
At eleven letters in length, Rupturewort is the longest word in the English dictionary that can be spelled by the top row of letters on a qwerty keyboard.

Of Interest:
Herniaria glabra is gently coumarin-scented. Coumarin is a fragrant chemical compound found in many plants, notably in high concentration in the tonka bean (Dipteryx odorata), vanilla grass (Anthoxanthum odoratum), sweet woodruff (Galium odoratum), mullein (Verbascum spp.), sweet grass (Hierochloe odorata), cassia cinnamon (Cinnamomum aromaticum) and sweet clover (Fabaceae spp.).
The name comes from a French word, coumarou, for the tonka bean. It has a sweet odour, readily recognised as the scent of newly-mown hay, and has been used in perfumes since 1882.
Sweet woodruff, sweet grass and sweet clover in particular are named for their sweet smell, which is due to their high content of this substance. It has been used as an aroma enhancer in pipe tobaccos and certain alcoholic drinks.